sched/wait, fs/fscache: Convert wait_on_atomic_t() usage to the new wait_var_event() API

The old wait_on_atomic_t() is going to get removed, use the more
flexible wait_var_event() API instead.

No change in functionality.

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: David Howells <dhowells@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>

fs/fscache/cookie.c

@@ -557,9 +557,10 @@ void __fscache_disable_cookie(struct fscache_cookie *cookie, bool invalidate)
 	 * n_active reaches 0).  This makes sure outstanding reads and writes
 	 * have completed.
 	 */
-	if (!atomic_dec_and_test(&cookie->n_active))
-		wait_on_atomic_t(&cookie->n_active, atomic_t_wait,
-				 TASK_UNINTERRUPTIBLE);
+	if (!atomic_dec_and_test(&cookie->n_active)) {
+		wait_var_event(&cookie->n_active,
+			       !atomic_read(&cookie->n_active));
+	}
 
 	/* Make sure any pending writes are cancelled. */
 	if (cookie->def->type != FSCACHE_COOKIE_TYPE_INDEX)

include/linux/fscache-cache.h

@@ -496,7 +496,7 @@ static inline bool __fscache_unuse_cookie(struct fscache_cookie *cookie)
 
 static inline void __fscache_wake_unused_cookie(struct fscache_cookie *cookie)
 {
-	wake_up_atomic_t(&cookie->n_active);
+	wake_up_var(&cookie->n_active);
 }
 
 /**